It is frequently desirable to test the performance of a component prior to installing the component in its intended environment. An integrated pressure management system is an example of such a component that may be tested before being installed on a vehicle. The integrated pressure management system performs a vacuum leak diagnostic on a headspace in a fuel tank, a canister that collects volatile fuel vapors from the headspace, a purge valve, and all the associated hoses and connections.
It is desirable to test components in an environment that simulates the intended operating environment. A simulated environment that is suitable for testing the vacuum leak diagnostic of integrated pressure management systems can include an adjustable vacuum level.
Known vacuum generating methods suffer from a number of disadvantages including the inability to generate vacuum levels in the desired testing range (i.e., conventional vacuum generators are not stable below two inches of water), the inability to precisely control the vacuum level, and the inability to perform a test in an acceptable period.
It is believed that there is needed to provide a device and a method that overcome the disadvantages of conventional vacuum generators.
The present invention provides a device for drawing a vacuum relative to an ambient environment. The device includes a member defining a passage, a valve, and a fluid communication conduit. The passage extends between a first end and a second end, and includes a constriction that defines an orifice. The first end is in fluid communication with the ambient environment. The valve has a first port and a second port. The first port is adapted for fluid communication with a pressure source at a first pressure level. The fluid communication conduit includes a fluid communication tap at a second pressure level. The second pressure level is responsive to fluid flow through the orifice. And the fluid communication conduit connects the second end of the member and the second port of the valve.
The present invention also provides a method of testing a vacuum detection device. The method includes providing a pressure source at a first pressure level, drawing a vacuum relative to an ambient environment with a vacuum generating device, connecting the vacuum detection device to a fluid communication tap, and regulating a second pressure level in response to varying fluid flow through an orifice. The vacuum-generating device includes a member that defines a passage, a valve, and a fluid communication conduit. The passage extends between a first end and a second end, and includes a constriction that defines the orifice. The first end is in fluid communication with the ambient environment. The valve has a first port and a second port. The first port is adapted for fluid communication with a pressure source at a first pressure level. The fluid communication conduit includes the fluid communication tap at the second pressure level. And the fluid communication conduit connects the second end of the member and the second port of the valve.